16967-02-5

[reaction: see text] Two new and very efficient procedures (Procedures A and B) are reported for the Pd-catalyzed cross coupling of aryl electrophiles with terminal alkynes via their in situ conversion into alkynylzinc derivatives. Procedure A is particul

In the present Letter the use of ionic liquids based on butylpyridinium salts (C4PyPF6, C4PyBF4, and C4PyNO3) is described in the Sonogashira reaction. Aiming the development of recyclable

A crystalline porous metal-organic framework Ni2(BDC) 2(DABCO) was synthesized and characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR), atomic absorption spectrophotometry (AAS), and nitrogen physisorption measurements. Ni2(BDC)2(DABCO) could be used as an efficient and recyclable heterogeneous catalyst for the cross-coupling reaction between phenylboronic acids and phenylacetylenes in the presence of molecular oxygen in air as the stoichiometric oxidant. High conversions of the cross-coupling products were achieved with no homo-coupling products being detected by GC. Ni2(BDC)2(DABCO) exhibited significantly higher catalytic activity in the coupling reaction than that of other Ni-MOFs such as Ni3(BTC)2 and Ni(HBTC)(BPY). Zn 2(BDC)2(DABCO) and Co2(BDC)2(DABCO) were found to be completely inactive for the transformation, while the reaction using Cu2(BDC)2(DABCO) as the catalyst led to the formation of a 10% homo-coupling product. To the best of our knowledge, a nickel-based catalyst was not previously used for the oxidative coupling reactions between phenylacetylenes and phenylboronic acids. the Partner Organisations 2014.

Phosphonium amino acid ionic liquids were found to be useful for the copper-free and amine-free Sonogashira coupling reaction. A hydrophobic and lipophobic ionic liquid permitted easy separation of the product from ionic liquid and catalyst, and the recov

The synthesis of two types of phosphine ligands that feature perfluorinated ponytails is reported. A bidentate (RfCH2CH2)2PCH2CH2P(CH2CH2Rf)2 (Rf = CF3(CFs

This research paper, reports the preparation of palladium impregnated [Zn2(BDC)2(4-bpdh)]3DMF (Pd@TMU-16) with a simple liquid impregnation-reduction method as a novel and efficient catalyst with the high catalytic performance for co

Inspired by the synthesis of triple-shelled periodic mesoporous organosilica hollow spheres, a straightforward and controllable approach for the preparation of Co3O4 NPs embedded in triple-shelled graphitic carbon nitride has been es

The synthesis of 1,3-oxazoles from symmetrical and unsymmetrical alkynes was realized by an iodonium cation-pool electrolysis of I2 in acetonitrile with a well-defined water content. Mechanistic investigations suggest that the alkyne reacts with the acetonitrile-stabilized I+ ions, followed by a Ritter-type reaction of the solvent to a nitrilium ion, which is then attacked by water. The ring closure to the 1,3-oxazoles released molecular iodine, which was visible by the naked eye. Also, some unsymmetrical internal alkynes were tested and a regioselective formation of a single isomer was determined by two-dimensional NMR experiments.

This work investigates the preparation of a catalytic complex of palladium nanoparticles supported on novel Schiff base modified chitosan-Unye bentonite microcapsules (Pd NPs@CS-UN). The complex has been characterized by FT-IR, EDS, XRD, TEM, HRTEM, Raman

An electrooxidative direct difunctionalization of internal alkynes with sulfonyl hydrazides has been developed for the construction of sulfonated enethers. In this transformation, metal catalysts or stoichiometric amount of oxidants are not required and molecular nitrogen and hydrogen are the sole byproducts, providing a simple and green approach for preparing various sulfonyl tetrasubstituted alkenes. Notably, the protocol could be efficiently scaled up and the follow-up procedures of the corresponding functionalized alkenes demonstrate the practicality of the electrochemical synthesis.

An intriguing pyridine-boryl radical-mediated C?H alkynylation reaction of inactivated alkanes was described. The reaction features mild operation condition and wide substrate scope, and affords the corresponding products in moderate to good yields. Notab

In this work, biosynthesized Fe3O4@Ni nanoparticles using Euphorbia maculata aqueous have been used as effective catalysts in the synthesis of 2,3-disubstituted benzo[b]furan derivatives using three component coupling of aldehydes, s

We present herein an unprecedented allylative dicarbofunctionalization of alkynes with allylic alcohols. This simple catalytic procedure utilizes commercially available Ni(COD)2, triphenylphosphine, and inexpensive reagents, and delivers valuable skipped dienes and trienes with an all-carbon tetrasubstituted alkene unit in a highly stereoselective fashion. Preliminary mechanistic studies support the reaction pathway of allylnickelation followed by transmetalation in this dicarbofunctionalization of alkynes.

Since its discovery in 1938, hydroformylation has been thoroughly investigated and broadly applied in industry (>107 metric ton yearly). However, the ability to precisely control its regioselectivity with well-established Rh- or Co-catalysts has thus far proven elusive, thereby limiting access to many synthetically valuable aldehydes. Pd-catalysts represent an appealing alternative, yet their use remains sparse due to undesired side-processes. Here, we report a highly selective and exceptionally active catalyst system that is driven by a novel activation strategy and features a unique Pd(I)-Pd(I) mechanism, involving an iodide-assisted binuclear step to release the product. This method enables β-selective hydroformylation of a large range of alkenes and alkynes, including sensitive starting materials. Its utility is demonstrated in the synthesis of antiobesity drug Rimonabant and anti-HIV agent PNU-32945. In a broader context, the new mechanistic understanding enables the development of other carbonylation reactions of high importance to chemical industry.

A palladium-catalyzed intermolecular dynamic kinetic asymmetric dearomatization of 3-arylindoles with internal alkynes was developed with the use of achiral Xantphos and chiral sulfinamide phosphine ligand (PC-Phos) as the co-ligands. This method could deliver various spiro[indene-1,3′-indole] compounds in good yields (up to 95 % yield) with up to 98 % ee. The salient features of the transformation include the use of readily available substrates, ease of scale-up and the versatile functionalization of the products. The mechanistic experiments gave some insights on active intermediates.

-

A new method of Sonogashira coupling reactions between diorganyl tellurides and terminal alkynes is reported. The coupling reactions are performed using Pd(dppf)Cl2 as a catalyst, CuI as a co-catalyst in the presence of K2CO3 in DMSO. The reactions are carried out at room temperature and completed within 2 h when phenyl acetylene is used as a terminal alkyne. For aliphatic terminal alkynes, such as 1-hexyne and 1-octyne, an elevated temperature and longer reaction time are needed for the completion of the reactions. This process results in good yields of Sonogashira coupling products which is applicable for diaryl, divinyl and dialkynyl tellurides but not applicable for dialkyl tellurides.

UIO-66-NH2-Gl?Pd nanocatalyst was successfully synthesized during post-synthetic modification (PSM) method and its application was investigated in the Sonogashira coupling reactions. Initially, UIO-66-NH2 was synthesized and identifi

New Fe3O4@SiO2 core-shell superparamagnetic nanoparticles functionalized by a bis-salophen Schiff base Pd complex were synthesized and employed as an efficient magnetic nanocatalyst in the Heck and Sonogashira cross coupling reactions. The synthesized nanostructures were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), dynamic light scattering (DLS), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), elemental analysis (CHN), cyclic voltammetry (CV), Brunauer-Emmett-Teller analysis (BET), and UV-vis spectroscopy. The morphology and size of the nanoparticles were investigated by FE-SEM and TEM analyses. Furthermore, the magnetic properties of the catalyst were investigated by VSM analysis. The loading content and leaching amounts of palladium on the catalyst were measured by inductively coupled plasma (ICP) analysis. Also, the thermal behavior of this magnetic heterogeneous catalyst was studied using a TGA instrument. This heterogeneous catalytic system showed a good performance in the coupling of aryl halides with alkynes (Sonogashira reaction) as well as aryl halides with alkene derivatives (Heck reaction). High to excellent yields were achieved for these C-C coupling reactions. The catalyst can be simply separated from the reaction media by an external magnet and reused for eight consecutive runs without any significant loss of activity. Finally, the kinetics of the reactions were studied in this work.

A novel heterogenized organometallic catalyst was synthesized by coordinating palladium with polyvinyl alcohol-functionalized Fe3O4@SiO2 nanospheres. This novel catalyst was characterized using Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscope, field emission scanning electron microscope, dynamic light scattering, UV–vis spectroscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray analysis, thermogravimetric analysis and inductively coupled plasma analysis. The prepared palladium nanoparticles supported on polyvinyl alcohol functionalized Fe3O4@SiO2 nanoparticles were successfully applied as a magnetically recyclable catalyst in Heck and Sonogashira coupling reactions in water. They showed remarkable activity toward aryl halides (I, Br, Cl) using very low palladium loading in excellent yields and demonstrated high TONs (mmol of product per mmol of catalyst). Also, the catalyst could be magnetically separated and reused seven times without any appreciable loss of catalytic activity.

We report an electrochemical protocol for the direct oxidation of internal alkynes in air to provide 1,2-diketones. A variety of functional groups and heterocycle-containing substrates can be tolerated well under mild conditions.

Transition-metal-catalyzed cross-coupling chemistry can be regarded as one of the most powerful protocols to construct carbon–carbon bonds. While the field is still dominated by palladium catalysis, there is an increasing interest to develop protocols that utilize cheaper and more sustainable metal sources. Herein, we report a selective, practical, and fast iron-based cross-coupling reaction that enables the formation of Csp?Csp3 and Csp2?Csp3 bonds. In a telescoped flow process, the reaction can be combined with the Grignard reagent synthesis. Moreover, flow allows the use of a supporting ligand to be avoided without eroding the reaction selectivity.

A highly efficient and convenient Negishi cross-coupling reaction has been developed for the synthesis of unsymmetrical alkynes and enynes in a continuous-flow process. The reaction proceeds through an in situ generated alkynylzinc reagent by the reaction of lithium acetylide with zinc halide at room temperature followed by a cross-coupling reaction with aryl or vinyl iodides. The notable features of this work compared to the conventional benchtop method are mild reaction conditions, good to excellent yields, broad functional-group compatibility, short residence time (73 sec) and especially desilylation of TMS group with the residence time of only 10.5 sec.

In this paper, a novel heterogeneous palladium catalyst was synthesized by anchoring N-heterocyclic carbene-Pd(II) complex based on theophylline on magnetic Fe3O4@SiO2 nanoparticles. The synthesized magnetic composite was characterized by fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray analysis (EDX), thermogravimetric analysis (TGA), vibration sample magnetometry (VSM), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS), N2 adsorption-desorption isotherm analysis (BET), UV–vis spectroscopy and elemental analysis. Also, loading content of palladium on the catalyst was measured by inductive coupled plasma (ICP) analysis. The synthesized catalyst was used successfully for the Suzuki cross-coupling reactions of various aryl halides (I, Br, Cl) with phenylboronic acids. This reaction was best performed in water as a green solvent in the presence of just 0.37–0.5 mol% of the catalyst at 60 °C. Also, we have reported this recyclable catalytic system as a stable phosphine-free Pd catalyst for the Sonogashira cross-coupling of aryl halides (I, Br, Cl) with terminal aromatic and aliphatic alkynes under solvent-free conditions. All coupling reactions proceeded with good to excellent yields. The catalyst showed good stability and was recovered and reused for eight reaction cycles without a significant loss in its catalytic activity. Also, the leaching of the catalyst has been examined by a hot filtration test and ICP-AES analysis.

In this study, a novel heterogeneous palladium catalyst was synthesized by anchoring palladium onto ethylenediaminetetraacetic acid (EDTA)-coated Fe3O4@SiO2 magnetic nanocomposite and used for the Suzuki and Sonogashira cross-coupling reactions. The properties of the magnetic catalyst were characterized by FT-IR, XRD, TEM, FE-SEM, DLS EDX, XPS, N2 adsorption-desorption isotherm analysis, TGA, VSM, elemental analysis and the loading level of Pd in catalyst was measured to be 0.51?mmol/g by ICP. The catalyst was used in Suzuki cross-coupling reactions of various aryl halides, including less reactive chlorobenzenes with phenylboronic acid without any additive or ligand under green conditions. Furthermore, we have reported this recyclable catalytic system for Sonogashira cross-coupling reactions of various aryl halides (I, Br, Cl) under copper and ligand-free conditions in the presence of DMF/H2O (1:2/v:v) as a solvent. The magnetic catalyst could also be separated by an external magnet and reused six times without any significant loss of activity.

A novel supported catalyst formed by an oxime-derived palladacycle supported on clay OxPdCy@clay is synthesized and characterized. This palladium composite promotes the Sonogashira reaction of aryl iodides, bromides and chlorides with terminal alkynes in polyethylene glycol200 at 85 or 130 °C using 0.05–0.1 mol% of palladium loading under copper and phosphine free conditions. This supported palladacycle, OxPdCy@clay, showed a superior catalytic activity than dimeric oxime-palladacycles. Mechanistic studies about the heterogeneous or homogeneous nature of the catalyst show that catalyst is working mainly under heterogeneous conditions. This supported palladacycle OxPdCy@clay can be recycled by simple centrifugation and reused for at least nine consecutive runs with small decrease in activity.

3,5-Bis((phenylselanyl)methyl)phenol has been synthesized as a novel SeCSe pincer type pre-ligand from commercially available 5-hydroxy isophthalic acid through a multistep synthesis. Then, a polystyrene-supported SeCSe pincer ligand and its corresponding palladium complex were prepared and characterized using different techniques including FT-IR, SEM/EDX, TG/DTG, and XPS. The amount of palladium incorporated into the polymer matrix as determined by ICP analysis was obtained to be 3.64 wt% (0.34 mmol g-1). The PS[PdCl-SeCSe] catalytic activity has been evaluated in the Sonogashira coupling of diverse aryl halides with aromatic and aliphatic terminal alkynes. It was also noted that less reactive and inexpensive aryl bromides and aryl chlorides have been successfully cross-coupled with terminal alkynes using low catalyst loading. Moreover, the developed methodology is effective for the stereoselective preparation of substituted 1,3-enynes.

In this work, a novel diethylenetriamine-functionalized-boehmite nanoparticle-supported Cu(I) catalyst is synthesized. The catalyst prepared is then characterized by FT-IR spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray

DNA nanotechnology has recently emerged as a powerful discipline with diverse applications. However, studies focused on the combination of DNA and metal nanoparticles for catalyst design are scanty. We have prepared a catalyst composed of palladium nanoparticles supported on DNA which has been characterised by TEM, SEM, EDX, UV, FTIR and XPS. The catalyst, mainly composed of Pd(ii) and Pd(iv) species in the form of oxides, has been effectual in the copper- and ligand-free Sonogashira-Hagihara coupling of aryl iodides with terminal aromatic and aliphatic alkynes. The products are obtained in 54-86% isolated yields using low catalyst loading (0.5 mol%) under mild conditions (65 °C) in methanol without air exclusion. Moreover, the catalyst can be easily recovered and reused in five cycles and shows better performance than an array of commercial palladium catalysts. The mechanistic aspects of the reaction are also tackled in detail.

Triarylsulfonium, alkyl- and fluoroalkyl(diaryl)-sulfonium, and aryl(dialkyl)sulfonium triflates are successfully used as a new family of cross-coupling participants in the Sonogashira reaction as aryldiazonium, diaryliodonium, and tetraphenylphosphonium salts. It was found that terminal alkynes reacted mildly with triarylsulfonium or (2,2,2-trifluoroethyl)diphenylsulfonium triflate at room temperature under Pdand Cu-cocatalysis to give the corresponding arylalkynes in up to >99% yield. This protocol represents the first use of arylsulfonium salts as cross-coupling partners in the Pd/Cu-catalyzed Sonogashira reaction.

The conversion of waste into high-value materials is considered an important sustainability strategy in modern chemical industries. A large volume of shell waste is generated globally from mussel cultivation. In this work, mussel shell waste (Perna viridis) is transformed into individual calcium carbonate plates (ICCPs) and is applied as a support for a heterogeneous catalyst. Palladium nanoparticles (3–6 nm) are deposited with an even dispersion on the ICCP surface, as demonstrated by X-ray diffraction and scanning electron microscopy. Using this system, Sonogashira cross-coupling reactions between aryl iodides and terminal acetylenes were accomplished in high yields with the use of 1 % Pd/ICCP in the presence of potassium carbonate without the use of any copper metal or external ligand. The Pd/ICCP catalyst could also be reused up to three times and activity over 90 % was maintained with negligible Pd-metal leaching. This work demonstrates that mussel shell waste can be used as an inexpensive and effective support for metal catalysts in coupling reactions, as demonstrated by the successful performance of the Pd-catalyzed, copper-free Sonogashira cross-coupling process.

Two new triphenylphosphine-cyclopalladated ferrocenylpyrazine complexes containing chlorine/iodine anion 2-3 have been easily prepared from the bridge-splitting reaction of the palladacyclic dimer 1 and anion exchange reaction, respectively. They were characterized by elemental analysis, IR, and 1H NMR. Additionally, the structures of these two complexes were determined by single-crystal X-ray analysis and C-H···N hydrogen bonds and π-π interactions were found in the their crystal structures. These complexes displayed good activity in the coupling of terminal alkynes with arylboronic acids under atmospheric conditions. This method provided the corresponding arylalkynes with good to excellent yields.

This study demonstrates a new synthetic strategy for the preparation of porous SiO2 for catalytic applications using natural and waste materials from rice husks as the source of biosilica. Biogenic porous silica nanoparticles with a mean diameter of 45 nm were successfully prepared from rice husk (RH) biomass via a new multistep method. During the first step, sodium silicate is extracted from rice husks. Then, cetyltrimethylammonium bromide (CTAB), HCl, and HOAc were added into sodium silicate solution, and the resulting mixture was sonicated. After the hydrothermal reaction, the collected samples were calcinated to obtain silica nanoparticles. Then, dendrimer-encapsulated Pd(0) nanoparticles supported on nano-silica with surface amino groups were fabricated. These materials are prepared by sequestering palladium ions within dendrimers followed by chemical reduction to yield the corresponding zero-valent palladium nanoparticles. The synthesized nanostructures were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), dynamic light scattering (DLS), N2 adsorption-desorption isotherm analysis, UV-vis spectroscopy and elemental analysis. The morphologies of the catalyst were characterized using a field emission scanning electron microscope (FE-SEM) and a transmission electron microscope (TEM). Also, its Pd content was determined by using an inductively coupled plasma (ICP) analyzer. This catalytic system was used as an efficient catalyst for Sonogashira reaction of aryl halides with alkynes under copper and phosphine ligand-free conditions in water. The catalyst was regenerated for five cycles of reaction without any significant loss in its activity. Also, the analysis of the reaction mixture by the ICP technique showed that the leaching of the catalyst was negligible.

An efficient Pd(OAc)2/Cu(Xantphos)I system for Sonogashira coupling is disclosed. Aryl bromides/iodides and electron-poor aryl chlorides were suitable for this reaction. The experimental results suggest that Cu(Xantphos)I plays a unique role in which the phosphine ligand coordinates with copper.

A highly efficient and easily recyclable magnetic nanoparticle supported palladium catalyst was developed and applied in the Heck and Sonogashira reactions in order to show its catalytic applicability in Pd-catalyzed C-C coupling protocols. The catalyst was prepared using a simple chemical process. First, the prepared Fe3O4@SiO2 nanoparticles were reacted with (3-chloropropyl)-trimethoxysilane (3-CPTMS) in order to synthesis chloro-functionalized magnetic nanoparticles (CPS-MNPs). The substitution reaction of synthetic NNN ligand with CPS-MNPs yields the production of CPS-MNPs-NNN ligand. Finally, immobilization of palladium species on CPS-MNPs-NNN ligand surface afforded CPS-MNPs-NNN-Pd catalyst. The structure and morphology of the prepared nanocatalyst was characterized using various methods such as SEM, TEM, XPS, EDX, CHN, ICP, XRD, FT-IR and VSM techniques. The TEM images show that the sizes of the palladium catalyst are in the range of 8-15 nm. The Heck and Sonogashira coupling reactions were performed in the presence of a catalytic amount of this catalyst system (0.5 mol%) and good yields of products were obtained. Due to the magnetic nature of the catalyst it can be separated from the reaction mixture easily by applying an external magnetic field. Heterogeneity tests affirmed that the catalytic activity stayed indefectible during multiple reaction cycles.

Bisindoles (BIMs) were modulated as powerful N,N′ donor ligands for the copper-catalyzed Sonogashira reaction. Ligand screening experiments on 11 BIM compounds found that 3,3′-(4-chlorophenyl)methylenebis(1-methyl-1H-indole) (10%) efficiently accelerated CuCl (5%)-catalyzed cross-coupling of aryl iodides with terminal alkynes. A wide range of substituted aryl iodides and/or alkyl- and aryl-substituted terminal alkynes were examined, leading to the corresponding coupling products with yields up to 99%. An efficient and scalable protocol for the synthesis of BIM ligands on a gram scale, with extremely low catalyst loading of o-ClC6H4NH3 +Cl?, was also developed with a reaction time of 20?min with yields up to 93%. This novel N,N′ ligand was air-stable, easily available and highly modulated with low copper loading. Copyright

Under the classic reaction conditions, a large excess of copper catalyst and N, O donor ligands were mandatory for the catalytic cross-coupling of Csp2-Csp bonds. Herein, we wish to report α,β-ynones as σ-, π-electron donating ligands for copper catalyzed Sonogashira-type reaction. As low as 0.25-2.5 mol% of L11 (3-(4-bromophenyl)-1-(4-methoxyphenyl)prop-2-yn-1-one) significantly accelerated the 0.1-1.0 mol% of CuI catalyzed cross-coupling of aryl iodides with terminal alkynes and alkynylcarboxylic acids, respectively. This low-mol% catalyst system showed satisfactory activity and tolerance with 36 examples of substituted alkynes.

A hydroxylamine modified polypropylene fibre [Pd(II)-AOFs] was synthesised and used to catalyse the Sonogashira reaction between phenylacetylene and iodobenzene. The results showed that highly efficient catalytic activity can be achieved for the cross-coupling reaction. More importantly, the reaction conditions are moderate and do not require inert gas protection. The catalyst could be readily extracted by simple operations and conveniently recycled four times without an obviously significant decrease in activity.

Abstract A novel MCM-41-immobilized Schiff base-pyridine bidentate copper(I) complex [MCM-41-Sb,Py-CuI] was conveniently prepared from commercially available and inexpensive 3-aminopropyltriethoxysilane via immobilization on MCM-41, followed by reacting w

A stable and highly efficient NiCl2(PPh3)2/CuI/PEG-400/H2O catalytic system for the Sonogashira reaction has been developed. In the presence of NiCl2(PPh3)2 and CuI, the coupling reaction of aryl iodides with terminal alkynes was carried out smoothly in a mixture of poly(ethylene glycol) (PEG-400) and water at 100C with K2CO3 as base to afford a variety of arylacetylenes in good to excellent yields. The isolation of the products was readily performed by extraction with petroleum ether, and the NiCl2(PPh3)2/CuI/PEG-400/H2O system could be easily recycled and reused six times without significant loss of catalytic activity. Our system not only avoids the use of easily volatile organic solvents but also solves the basic problem of catalyst reuse.

A magnetically separable nanocatalyst prepared by incorporating Pd nanoparticles onto CoFe2O4 magnetic nanoparticles was found to be very effective in catalyzing Sonogashira cross-coupling reactions. In this green synthetic process, it is not necessary to use an external linker to support the palladium nanoparticles onto the cobalt ferrite matrix. The catalyst is effective without the use of any ligand or copper additive. The reaction works smoothly in ethanol at 70 °C with both aryl iodides and bromides to produce corresponding product in high yield. After completion of the reaction, the catalyst could be easily separated using an external magnet and reused up to five catalytic cycles with sustained catalytic activity.

Sub-nanometric Cu clusters formed by endogenous reduction of Cu salts and Cu nanoparticles are active and selective catalysts for C-N, C-C, C-O, C-S, and C-P bond-forming reactions. Sub-nanometric Cu clusters have also been generated within a polymeric film and stored with full stability for months. In this way, they are ready to be used on demand and maintain high activity (TONs up to 104) and selectivity for the above reactions. A potential mechanism for the formation of the sub-nanometric clusters and their electronic nature is presented.

A dinuclear copper complex containing N,N′-diquinolylformamidinate and a tetranuclear copper complex containing N,N′-diquinolylacetamidinate were synthesized. The structure of complexes was confirmed by X-ray analysis, showing that copper atoms were bridg

Abstract A simple Pd-catalyzed Sonogashira-type cross-coupling reaction using of triarylbismuthanes is described. The reaction of triarylbismuthanes with terminal alkynes in the presence of 5 mol% of Pd(OAc)2, 6 equiv. AgF and 6 equiv. K3PO4 at room temperature afforded the coupling products in good to excellent yield. The reaction proceeded effectively under aerobic conditions, and all three aryl groups on bismuth could be transferred to the coupling products. The reaction was sensitive to the electronic nature of the triarylbismuthanes: substrates bearing an electron-withdrawing group on the aromatic ring showed higher reactivity than those having an electron-donating group.

A palladium-catalysed Hiyama cross-coupling reaction of alkynyl halides with aryltrialkoxysilanes has been developed. Catalysed by bis(dibenzylideneacetone)palladium and in the presence of silver fluoride and potassium bicarbonate, a variety of alkynyl halides (I, Br and Cl), whether electron-deficient or electron-rich, underwent the cross-coupling reaction with aryltrialkoxysilanes at room temperature to afford the corresponding alkynes in moderate to good yields.

A novel poly(vinyl chloride)-supported Pd complex was found to be a highly active catalyst for the Heck and Sonogashira reactions of aryl halides under aerobic conditions. The complex is thermally stable, and can be easily recovered and reused. The catalyst was recycled for the Heck and Sonogashira reactions for five runs without appreciable loss of its catalytic activity, and with negligible metal leaching.

Two easily accessible hydrazinoaminocarbene complexes of Pd(II) are shown to be efficient catalysts for copper-free Sonogashira cross-couplings of a variety of aryl iodides with aryl- and alkylalkynes under mild conditions, in ethanol as the solvent and u

Copper-catalyzed arylcarbocyclization reaction of alkynes was realized with diaryliodonium salts through C-C bond formation on an inert C(sp3)-H bond. This method provides an efficient cyclization of alkyl alkynes to generate carbocycles with good step-economy. Theoretical study revealed an interesting Cu-catalyzed concerted pathway of the C-C bond formation.

Alkynes serve as prevalent intermediates in the synthesis of natural products and pharmaceuticals. We here described a new and efficient route to internal alkynes by Pd-catalyzed Kumada cross-coupling reactions of alkynyl halides with Grignard reagents. In the presence of Pd(PPh3)4 and N 1,N 1,N 2,N 2-tetramethylethane-1,2-diamine (TMEDA), a variety of alkynyl halides underwent Kumada coupling with Grignard reagents, giving the corresponding internal alkynes in moderate to good yields. A new Pd-catalyzed Kumada cross-coupling reaction of alkynyl halides with Grignard reagents has been developed. This transformation provides a new, experimentally simple access to internal alkynes in good yields, and it can accommodate a broad range of substrates with excellent functional group tolerance and good levels of selectivity control.

We describe a convenient method for the synthesis of 1,2-disubstituted acetylenes via a cross-coupling reaction of (bromoethynyl)benzene with Grignard reagents. The reaction of (bromoethynyl)benzene (1 mmol) with Grignard reagent (1.3 mmol) mediated by NiCl2 (4 mol%) and (p-CH3Ph)3P (8 mol%) in THF could produce 1,2-disubstituted acetylenes in good yields at room temperature.

L2Pd(0) and L2Pd(II) complexes, where L= t-Bu 2(p-NMe2C6H4)P, have been identified as efficient catalyst systems for the Heck alkynylation of a variety of aryl bromides (17 examples) and aryl/heteroaryl chlorides (31 examples) with a range of aryl- and alkyl-acetylenes in excellent yields, under relatively low Pd loadings. The single-crystal X-ray structure determination of the presumably active catalytic species, L2Pd(0), was carried out in this study to better understand the superior activity of the current catalyst system from a structure-activity relationship point of view. The P-Pd-P bond angle indicates that the complex is bent (174.7) in comparison to the perfectly linear (180.0) structure of the analogous Pd(t-Bu3P)2. Preliminary mechanistic studies on the negative copper effect and substrate effect of aryl acetylenes were conducted to better understand the cross-coupling pathway of Heck alkynylation.

A 'F'lurry of activity: The title reaction provides a convenient procedure for direct synthesis of perfluoroalkylated phosphines. The synthesized phosphine n-C10F21PPh2 forms a complex with palladium(II) to give 1 and several runs of coupling reactions are attained with n-C10F21PPh2 by using a fluorous/organic biphasic system. Copyright

The air-moisture stable and recyclable palladium(II) Schiff base complex anchored to multi-walled carbon nanotubes (PdeSchiff base@MWCNTs) behaves as a very efficient heterogeneous catalyst in the SuzukieMiyaura coupling of arylboronic acids and aryl halides, and the SonogashiraeHagihara reaction of aryl iodides and terminal alkynes in aqueous media to afford the corresponding CeC couplings in high yields.